Designed to travel as an unmanned aircraft system (UAS) at Mach 6, six times the speed of sound, the SR-72 will go twice the speed of the SR-71, which was retired in the late 1990s. Powered by combined-cycle engine technology, the Skunk Works team has been working with propulsion engineers from Aerojet Rocketdyne on the project for several years.

In a statement, the Skunk Works team called the aircraft a "game changer," taking design notes from the rocket-launched Falcon Hypersonic Technology Vehicle 2 (HTV-2). The HTV-2 was developed in joint collaboration with the Defense Advanced Research Projects Agency (DARPA), and traveled at a top speed of Mach 20, or 13,000 mph.

"Hypersonic aircraft, coupled with hypersonic missiles, could penetrate denied airspace and strike at nearly any location across a continent in less than an hour,” said Brad Leland, program manager of hypersonics at Lockheed Martin. “Speed is the next aviation advancement to counter emerging threats in the next several decades. The technology would be a game-changer in theater, similar to how stealth is changing the battlespace today.”